The present invention relates generally to seam plates for use in connection with the retention of roof decking membranes upon roof decking substructures at seam locations defined between separate, adjacent, and overlapping membrane members, and more particularly to a new and improved seam plate, and a roof decking system employing the same, wherein improved retention of the membrane member upon the roof decking substructure is able to be achieved without generating or initiating tearing or other similar deterioration of the roof decking membrane when the membrane is subjected to wind or other environmental forces.
Stress plates or seam plates are used in connection with the retention of roof decking membranes upon roof decking substructures at seam locations defined between separate but adjacent or overlapping membrane members, and are of course well-known in the art. Examples of such seam plates or stress plates are disclosed within U.S. Pat. No. 4,945,699 which issued to Colin R. Murphy on Aug. 7, 1990, as well as U.S. Pat. No. 4,787,188 which also issued to Colin R. Murphy on Nov. 29, 1988. As disclosed within FIGS. 1, 3A-3C, and 4 of the aforenoted U.S. Pat. No. 4,945,699 to Murphy, the roof decking substructure is disclosed at 103 and may conventionally be provided with overlying insulation 102. The insulation 102 is, in turn, adapted to have membranes disposed thereon in an overlying manner, and at a location or site at which separate and adjacent membranes are to be in effect seamed together in an overlapping manner, a first underlying membrane is disclosed at 101 and is adapted to be secured to the underlying deck substructure 103 by means of a screw fastener 107 passing through a seam plate or stress plate 10, while a second membrane member 104 is adapted to be secured in an overlapping manner upon the first underlying membrane member 101 by means of a welded seam 111. The seam plate or stress plate 10 is seen to have a circular configuration, and is provided with an upper surface 11 and a lower surface 12. A central aperture 15 is provided for passage therethrough of the screw fastener 107, and a circular reinforcing rib 14 annularly surrounds the central aperture 15. Accordingly, when such a stress plate or seam plate 10 is to be used to secure membrane members to the underlying decking substructure 103, the stress plate or seam plate 10 is disposed atop the first underlying membrane member 101, and the stress plate or seam plate 10 is then fixedly secured to the underlying decking substructure by means of screw fastener 107 being threadedly engaged with the underlying decking substructure. In accordance with the particularly unique stress plate or seam plate 10 as disclosed within the noted Murphy patents, the bottom surface 12 of the stress plate or seam plate 10 is provided with a plurality of circumferentially spaced prongs or tangs 21 each of which terminates in a gripping point 22. The prongs or tangs 21 each have a substantially triangular configuration and are in effect partially punched-out or otherwise cut from the bottom surface portion 12 of the plate 10, and are subsequently bent such that the prongs or tangs 21 attain their desired disposition with respect to the bottom surface portion 12 of the plate 10. Such prongs or tangs 21 will therefore grip the lower or underlying membrane sheet 101 and prevent the same from becoming loose or free with respect to the stress plate 10 or the underlying roof substructure 103 despite wind or other environmental forces being impressed upon the membrane sheet 101.
While the aforenoted stress or seam plates of Murphy have been satisfactory and commercially successful, it has been experienced that, despite well-meaning statements of intent to the contrary as set forth in the Murphy patents, the presence of the pointed prongs or tangs 21 characteristic of the stress plate or seam plate 10 of the Murphy patents do in fact tend to puncture, tear, weaken, and otherwise cause deterioration of the membrane sheets 101 under wind and other environmental conditions. Obviously, such a state is not satisfactory in view of the fact that eventually, the membrane sheets tear away from the overlying seam plate 10 as well as away from the underlying insulation panel and roof decking, with the consequent result being the compromise of the structural integrity of the entire roof decking system.
A need therefore existed in the art for a new and improved stress plate or seam plate wherein the stress plate or seam plate could satisfactorily engage the insulation-protection membrane sheets so as to secure the membrane sheets to the underlying decking substructure, and yet, the means formed upon the stress plate or seam plate for engaging the membrane sheets would not tend to initiate tearing of the membrane sheets and thereby cause separation of the membrane sheets with respect to the stress plate or seam plate as well as the underlying decking substructure under, for example, windy or other forceful environmental conditions. Accordingly, the invention embodied within aforenoted U.S. patent application Ser. No. 09/933,230 was developed wherein, contrary to the PRIOR ART stress plate having the sharp-pointed prongs or tangs provided thereon, a plurality of circumferentially spaced, downwardly extending projections having substantially V-shaped cross-sectional configurations were provided upon the underside of the seam or stress plate wherein the projections comprised substantially rounded or radiused apices so as not to puncture or rupture the membrane sheets, and yet such projections could satisfactorily engage the membrane sheets so as to fixedly retain the same upon the underlying roofing deck substructural assembly.
While the seam plate or stress plate developed in accordance with the principles and teachings of the invention as set forth within the aforenoted U.S. patent application Ser. No. 09/933,230 has performed quite satisfactorily and has been commercially successful, it has been determined that such stress plate or seam plate cannot necessarily optimally accommodate all uplifting wind load forces, or ensure the maintenance of the membranes in their secured state upon the underlying insulation panel, as functions of, or interdependent upon, the particular membranes being employed. For example, the weather protection membranes have conventionally comprised membranes having a width dimension of approximately six feet (6.00xe2x80x2), however, within recent times, and in accordance with new industry standards or norms, membranes having width dimensions on the order of, for example, nine feet (9.00xe2x80x2), seem to be utilized more often. Consequently, such newer membranes comprise or cover square footage areas which are substantially fifty percent (50%) greater than those of the conventional or previously utilized membranes, and accordingly, such larger membranes represent or generate enhanced wind loads or forces acting upon the membranes, the seam or membrane plates, and the bolt fasteners securing the membranes and the seam plates to the underlying insulation panels and roof decking. Therefore, membrane and bolt fastener assembly failures are likely to increase, unless the aforenoted problems are adequately addressed. A proposed solution to the problem has been to simply increase the number of attachment sites at which the seam plates and bolt fasteners can be secured to the underlying insulation panels and roof decking, however, this is not a viable solution for several reasons.
For example, the number of attachment sites, or more particularly, the array or arrangement of the attachment sites, is predetermined, or in effect dictated, by means of the underlying roof decking in view of the fact that the bolt fasteners must be threadedly engaged within the crest portions of the roof decking. Conventionally, the predetermined distance defined between adjacent corrugations of the roof decking, as measured, for example, from crest to crest, is six inches (6.00xe2x80x3), and in accordance with conventional techniques for affixing the membranes to the underlying roof decking, the seam plate and bolt fastener assemblies are secured to alternative crest portions of the roof decking such that the predetermined distance defined between adjacent seam plate and bolt fastener assemblies is twelve inches (12.00xe2x80x3). Therefore, if additional attachment sites, at which additional seam plate and bolt fastener assemblies would be installed, were to be employed, the additional seam plate and bolt fastener assemblies would be installed within those crest portions of the roof decking which do not currently have seam plate and bolt fastener assemblies installed therein, thereby effectively doubling the number of seam plate and bolt fastener assemblies used to secure the membranes to the underlying roof decking. However, the effective doubling of the seam plate and bolt fastener assemblies renders the attachment system prohibitively expensive in terms of both hardware costs as well as man-hour installation costs.
A need therefore exists in the art for a new and improved seam plate for retaining roof decking membranes at their installed positions upon underlying insulation panels and roof decking wherein the new and improved seam plate will comprise structure integrally incorporated therein for effectively counteracting uplifting wind load forces acting upon the membranes, and therefore, in turn, acting upon the seam plate and bolt fastener assemblies attaching the membranes to the underlying insulation panels and roof decking, for effectively tailoring the structure of the seam plate for use in connection with different membranes having different strength or resistance properties or characteristics, for enabling different sections or regions of the seam plate to effect different gripping or retaining forces upon the membranes so as to, again, counteract uplifting wind load forces acting upon the different sections or regions of the seam plate, and for optimally reducing the tendency of any tearing to occurrence within the membranes, as well as the propagation of any tears within the membranes, under uplifting wind load force conditions.
Accordingly, it is an object of the present invention to provide a new and improved seam plate for use in connection with the fixing or securing of membrane sheets to underlying roof decking substructures.
Another object of the present invention is to provide a new and improved seam plate for use in connection with the fixing or securing of membrane sheets to underlying roof decking substructures wherein the seam plate effectively overcomes the various operational disadvantages or drawbacks characteristic of conventional PRIOR ART seam plates.
An additional object of the present invention is to provide a new and improved seam plate for use in connection with the fixing or securing of membrane sheets to underlying roof decking substructures wherein the seam plate effectively overcomes the various operational disadvantages or drawbacks characteristic of conventional seam plates by providing the seam plate with a substantially rectangular configuration so as to be capable of optimally counteracting the directional characteristics of the uplifting wind load forces which are impressed upon the underlying membrane sheets and which are therefore, in turn, transmitted to the seam plate and bolt fastener assemblies fixedly securing the underlying membrane sheets to the underlying insulation panels and roof decking.
A further object of the present invention is to provide a new and improved seam plate for use in connection with the fixing or securing of membrane sheets to underlying roof decking substructures wherein the seam plate effectively overcomes the various operational disadvantages or drawbacks characteristic of conventional seam plates by having different rib structure integrally incorporated therein so as to impart various reinforcing and bending or flexibility characteristics to the seam plate as functions of, or with respect, to the various characteristics or parameters of the membrane sheets, under such aforenoted uplifting wind or other environmental force conditions.
A last object of the present invention is to provide a new and improved seam plate for use in connection with the fixing or securing of membrane sheets to underlying roof decking substructures wherein the seam plate effectively overcomes the various operational disadvantages or drawbacks characteristic of conventional seam plates by having integrally incorporated therein different downwardly extending projections for engaging the underlying membrane sheets, and wherein further, the downwardly extending projections can have different configurations, different depth dimensions, and are located along different longitudinal linear loci of the seam plate so as to exhibit or generate different membrane-gripping properties or characteristics, to reduce the tendency of any tearing to occur within the membranes, and to prevent the propagation of any tears within and throughout the membranes, under the uplifting wind load force conditions.
The foregoing and other objectives are achieved in accordance with the teachings and principles of the present invention through the provision of a new and improved seam plate which has a substantially rectangular configuration so as to optimally accommodate and counteract the directional characrteristics of the uplifting wind load forces impressed upon the underlying roof decking membrane sheets. In addition, the seam plate comprises different substantially elongated centralized rib structure for imparting different stiffness and flexibility characteristics to the seam plate so as to in turn accommodate, and thereby render the same operationally compatible with, different membrane sheets having different strength, abrasion resistance, and tear-resistance characteristics or properties. Still further, the seam plate comprises a plurality of downwardly extending projections, which are adapted to operatively engage and thereby grip the underlying membrane sheets so as to retain the same at their predetermined positions atop the insulation panels and roof decking, wherein the projections have rounded apices so as not to readily cut or tear the membrane sheets, and wherein further, the projections have various depth dimensions so as to generate or exhibit different membrane-gripping forces. Still further, the projections are disposed upon predeterminedly scattered or dispersed regions of the seam plate located along different longitudinal and transverse linear loci so as to reduce the tendency of any tearing to occur within the membrane sheets, as well as to effectively prevent the propagation of any tearing of the membrane sheets throughout the entire extent of the membrane sheets, as a result of the non-concentration of loading at or upon predetermined membrane sheet locations.